Lithium base greases



Patented'Dec. 4. ess

UNITED .srA rEs PATENT. omes asoosso i No Drawing- Application January 22, 1M2,

- Serial No. 427,724

10 Claims. gel. 252-36) This invention' relates improvements in about 5. parts of lithium stearate and 1.5 parts lithium base lubricants, and more particularly of aluminum stearate. These soaps were thorf adapted for use at extremely low tem- 8 mixed with the oil and the heating 0nperatures and containinglithlum soaps.

tinued until a temperature of about 450 1'. was

. In'themanui'acture of lubricating-greases, con- 6 fl t lin I! des f m t f n antisideration is almost invariably iven to at least oxidant compound, and from 0.5 to 1% oiv a pour the general purposeffor which the grease i t point depressant may be added to the mixture be used. Some greases are made for specific t. th s ti After the desired proportions types of bearings or conditions, but so far as these materials were'added to the mixture, the known, very little has been done toward th lO heatingwas discontinued and thte final mixture development of ,greases adapted for use over quickly cooled in thin layers downto normal liei'fltii es r ing from above normal to extemperaturetremely low temperatures. A very pressing sta The resulting product had a lower utilization lem in this connection is the provision orgr point of minus and showed the following for 'use'in aircraft where the grease should be Pr Derties: V I g M 1e and plastic at temperatures ranging from worked netmflo T M 330 m F- to p atures as low as minus m m m A. 5 M I 3 5' to minus ordinal? greases are stable Se ration, 50 hours'at 150 F.. rcent- 0.5 at the higher temperatures, but at low temperav De tures even around zero degrees l 'ahrenheit many Example 3 become hardand stiff, and not only fail A light grease was also made by the prfl to lubricate, but make operation of the equip-' outlined in Example No. l, by heating about ment extremely diilicult. parts of a naphthenic base lubricating oil stock,

Lithium soaps have been found to give greases having a Saybolt Universal viscosity at F. which are stable and plastic over the wide temof 200 econds, and adding 5 parts of lithium perature ranges referred to above. Greases made stearate, about 1 part of aluminum stearate and from lithium soaps are especially adapted for about one-part ofrubber latex. The tempera- -lubricating various bearings of aircraft in which tllres employed, and cooling, was substantially a grease must be used instead of liquidlubricants. I the same as in Example No. 1 and the resulting Grease?1 rlrlinade from sodium and potassium soaps {grease showed the following properties:

are we own, but they do not have the prop-};

erty or being stable and plastic over the temggg f 'f 2 3. 3%: perature ranges indicated. While many broad r 2""? proposals have been made for using alkali hours at F f None metal" soaps in greases (and lithium is an alkali 35 ;i The use of. rubber latex or its equivale t i metal), the use of lithium soaps in greases, in "proves the colloidal dispersionjof the constituthe proportions given below, is believed to be 'ents. and the stabi i y d oothne s of t e new. 'Likewise, the property of specific propor- 8113 5 11 1 11 6 01' prevents bleedingtions of lithium soaps to impart stability and 40 Example Na 3 plasticity to greases over wide ranges of temperatures, including relatively low sub-zero tem- A medium grease was prepared by 93 peratures is believed to be an important discovparts same lubricating k as 'ery' in connection with the present invention. Example and mixing therewith about 7 I The features of the invention may be illustrated by reference to the following examples mmum steamm' The resulting grease m of grease compositions containing lithium soaps following pmpemes:

partsofilithium stearate and 1.5 parts of aluv in which the quantities of the various materials Worked penetration A. S. T. M 282- aregiven in parts by weight, except as indicated. Dropping point A. S. T. M .3 IL. 386

p Example Na 50 Separation, 50 hours at 150 F None A light grease useful at extremely low tem- E 4 peratures was prepared by heating about 95 parts 7 Arelatively thick grease was prepared by using of mixed base lubricating oil stock, having a about-89 parts of the lubricating oil stock used Saybolt viscosity at l00 F. of 72 seconds, to a 55 in Example No. 2, together with about 11 parts temperature of about 300 1 2, and then adding of lithium stearate and 1.5 parts of aluminum factory grease products.

properties:

Workedpenetration A. S. T. M ,244 Dropping point A.'S. T. M FL; 395 Separation, 50 hours at 15091 None The grease compositions of Examples Nos. 2, 3

and 4 may include, and preferably do include, an anti-oxidant and a pour point depressant, as in the case of the grease of Example No. 1. Any of the various commercial anti-oxidants or anticorrosion agents may be used, such for example as. tributyl phosphite and other organic phosphorus compounds. Triphenyl v and tricresyl phosphites may be used. Many anti-oxidants act as corrosion inhibitors or prevent the catalytic activity of metals. Any of theother-known anti-. oxidants maybe employed. The condensation product of chlorinated wax and naphthalene,

' usual conditions need not be greater than the limits mentioned in Example No. 1, which are given in percentages by weight based on the weight of the mixture of oil stock andsoap ingredients.

The oil stocks used for making various grades of grease in accordance with the present invention may vary in viscosity from about '70 to 200 seconds and higher, and the oils are preferably of mixed base or naphthenic base type, such as Mid-Continent and California lubricating oil stocks. A very satisfactory greas e has been made from steam cylinder stock, using 95 parts of such stock to five parts of lithium stearate, two parts of aluminum stearate, and two parts of rubber latex. lithium stearate may be varied from about four to about twelve parts, with a corresponding change in the proportion of cylinder stock. The lubricating oil stocks used preferably have a low pour point of at least about zero degrees Fahrenheit. Very satisfactory results were obtained with stocks of zero degrees Fahrenheit pour point.

While lithium stearate is the preferred lithium soap, it is to be understood that the lithium salts of other fatty acids of high mol weight may be used, preferably the salts of unsaturated fatty acids. The proportion of lithium soap in the grease mayvary from about four to about twelve parts by weight to from ninety-six to about eighty-eight parts by weight of lubricating oil stock. The commercial stearic acid used for making the lithium stearate in one instance con-- tained as much as 25% of palmitic acid so that a mixture of salts resulted which gave very satis- In general, it is preferred to make the lithium soaps directly from relatively pure or commercial fatty acids, using either lithium carbonate or lithium hydroxide of at least about 95% purity for making the salts. However, a lithiumv soap ofcastor oil has been found satisfactory. Various known fatty acids may be used such as lauric, myristic, linoleic, pe-

troleum acids, or fatty acids made from mineral oils, as for example by oxidation. Lithium naphthenates however are preferably used in ad- I dition to a lithium soap because of their greater solubility in the lubricating oil stock and their tendency to stabilize the dispersions of soaps and other ingredients in the oil stock. The propor- In this composition, the proportion of stearate. The resulting grease had the following v tion a the lithium naphthenate used should in general be less than the proportion of soap and may vary from about 0.1%, to about 1.5% of the mixture.

, The proportion of aluminum soap employed in the grease may vary from about 0.5% to about 3% of the mixture and is preferably a relatively pure product. While aluminum stearate is p ferred, the aluminum derivatives of other fatty acids such as oleic, palmitic, myristic, acids made from mineral oils and others may be used. The primary functions of the aluminum soap is to prevent or greatly reduce the bleeding, of the grease and to increase the colloidal dispersion of the other ingredients of the mixture.

Any of the greases made in accordance with the present invention may include from 0.5% to about 2.5% by weight of rubber latex or its equivalent. In mostfcases about 1% of latex is sufficient and is preferably used in makingsome of the lighter greases. Natural or synthetic rubber may be used in place of latex, such as balata, gum rubber, chlorinated rubber, butyl rubber and other elastic organic compounds any of which is included under the general-term "rubber as used herein.

The proportions of the various ingredients may be varied as illustrated by the examples, to provide a grease of desired penetration and dropping point which will be suitable for the particular bearings used and the low temperatures to be encountered. The penetration may vary from about 350 to about 220 and the dropping point from about 345 to 415 F.

It is to be understood that although the features of the invention have been described and illustrated in connection with certain examples, the invention is not restricted, except by the prior art and the scope of the appended claims.

Having thus described the features oi. the invention and illustrated the same with a number of specific examples, what is claimed as new is: 1. A lubricating composition comprised principally of a lubricating oil, from about 4% to about 12% by weight of a lithium soap, from about 0.5 to 3% by weight of an aluminum soap, and from about 0.5 to 2.5% by weight of a rubbar as an agent for preventing the bleeding of the grease composition. V

r 2. A lubricating grease comprised mainly of lubricating oil, from 4 to 12 per cent by weight of lithium stearate, from 0.5% to 2.5% of a rubber, and from 0.5 to 3 by weight of aluminum stearate for increasing the colloidal dispension of the lithium stearate therein.

3. A lubricating grease composition comprised essentially of from about four to six parts by weight of a lithium soap, from about 0.5 to 1.0 part by weight of an aluminum soap for increasing the colloidal dispersion of the other constituents of the grease, from about 0.5 to 2.5 parts by weight of a rubber. and from about ninety-four to ninety-six parts by weight of a lubricating oil.

4. A lubricating grease composition comprised essentially of from about four to six parts by weight of lithium stearate, from about 0.5 to one partby weight of aluminum stearate for increasing the colloidal dispersion of the other constituents of the grease, about one part by weight of latex, and from ninety four to ninety six parts by weight of a lubricating oil.

5. A lubricating grease comprised mainly of a lubricating oil, from 10% to 12% by weight of lithium stearate, about 1% by weight of a rubher, and from 2% to 3% by weight of an al num soap ior increasing the colloidal dispersion of the lithium stearate in theoil and for reducing the bleeding of the grease.

0. A lubricating grease composition useable at temperatures 01' from minus 60' to minus '10 1". comprised mainly of a lubricating oil, from 4% to 12% by weight of a lithium soap, and from 0.1% to 1.6% by weight of lithium naphthenate as a stabilizing agent for the mineral oil and v lithium soap.

7. A lubricant comprised principally of a lubricating oil and containing from about 4% to about 12% by weight oi a lithium soap oi castor oil and a relatively small but suillcient proportion of lithium naphthenste as a stabiliaer for the oil and soap.

8. A lubricating composition comprised prinso 3. cipa ly oialubricatinsoiLiromaboutifi to.-

about 12% by weight of a lithium soap, from about 0.5% to 2.6% by weight of a rubber, and a relatively small but suillcient'proportion or a 5 lithium naphthenate as a solubilising and stabilizing mat.

9. A lubricating grease comprised mainly ot a lubricating oil, from 4% to 12% by weight or a lithium soap. from 0.5% to 3% by weight or an aluminum soap, and from 0.1% to1.5% by weight 0; a lithium naphthenate as a stabilizing agent for. the mineral oil and soaps.

10. A lubricating grease comprised mainly of a lubricating oil, from 4% to 12% by weight of a lithium soap, from 0.5% to 2.5% of a rubber. and from 0.1% to 1.5% by weight of a lithium naphthenate as a stabilising agent for the grease.

JOHN D. ROMAN; 

